What might wilting and marginal burning in plants indicate about fertilizer application?

Wilting and marginal burning in plants can often indicate problems related to excess fertilizer salts. When plants are exposed to high concentrations of salt from fertilizers, especially when over-applied, it can lead to osmotic stress. This stress makes it more difficult for plants to absorb water, leading to symptoms such as wilting despite the presence of water in the soil.

Additionally, the buildup of excess salts can cause tissue damage, which manifests as browning or burning at the leaf margins. This is because the plant is essentially "burned" by the high salt levels, leading to dehydration and damage to the foliage. As a result, the symptoms of wilting and marginal burning are strong indicators that the plant may be suffering from salt stress due to excessive application of fertilizers.

In contrast, while an excess of macronutrients could contribute to some nutrient imbalances, it is the concentration of salts that directly leads to the observed wilting and burning symptoms. A lack of sunlight generally affects growth and can cause plant stunting rather than direct burning or wilting. Insufficient water contributes to wilting but does not typically result in marginal burning, which is more directly related to the soil salinity issues caused by over-fertilization.